Effects of caffeine on glucose tolerance: a placebo-controlled study.

OBJECTIVE: The investigation was performed to study the effects of 200 mg oral caffeine on glucose tolerance. DESIGN: Single-blind Latin square with active treatment (caffeine) and placebo. SETTING: The University of Padova, Department of Internal Medicine. SUBJECTS: 30 nonsmoking healthy subjects aged 26-32 years who abstained not only from coffee but also from tea, chocolate and cola for 4 weeks and who had given their informed consent. INTERVENTIONS: A 75 g oral glucose tolerance test (OGTT) was performed after giving caffeine or placebo (highly decaffeinated coffee). RESULTS: The glycaemic curve was normal in all subjects and was similar in the two groups until the second hour; in subjects taking caffeine a shift towards the right was detected at the 2nd, 3rd and 4th hours in comparison to those taking the placebo. Blood insulin levels were comparable after caffeine and after placebo along the entire OGTT. CONCLUSIONS: The data suggest that caffeine intake induces a rise in blood glucose levels that is insulin independent.

Hemodynamics following real and hypnosis-simulated phlebotomy.

Forearm arterial flow was measured in 22 healthy first-time blood donors during a 300-ml. blood letting and during the subsequent recovery. Blood pressure (BP) was also taken simultaneously and forearm peripheral resistance calculated. Following a transient BP and flow increase due to tachycardia related to needle insertion, both systolic BP and flow progressively and significantly decreased, while resistance increased. In a further 22 sex- and aged-matched highly hypnotizable subjects, blood donation was simulated by means of verbal hypnotic suggestions. The BP, flow and resistance curves were similar to those obtained with the real blood letting, without any between-subject difference or group/time interaction. Mere hypnosis without suggestion of phlebotomy and the simple bed resting did not produce any effect. These results indicate that the hemodynamic changes observed during and after a blood loss are partly due to mental involvement rather than merely to the hydraulic effects of the removal of blood.

Effect of two different therapeutic approaches on total and cardiovascular mortality in a Cardiovascular Study in the Elderly (CASTEL).

Although limited numbers of elderly subjects have occasionally been included in population-based studies, only a few studies have been conducted specifically on elderly hypertensives, and practically none at a population level. We studied 655 hypertensive subjects from a cohort of 2,254 elderly subjects. The intervention consisted of the creation of a Hypertension Outpatients' Clinic under our auspices but with complete co-operation from general practitioners, randomizing the identified hypertensive patients into pre-established therapeutic drug regimens, and early follow-up recording of mortality for 7 years. The drugs used were clonidine (n = 61), nifedipine (n = 146) and the fixed combination of atenolol+chlorthalidone (n = 144); 304 subjects underwent "free therapy" by their personal physicians without any special intervention. There were 1,404 normotensive subjects. Overall 7-year follow-up mortality was 34.9% in the hypertensive subjects receiving "free therapy", 22.5% in those receiving "special care", and 24.2% in the normotensives. Cardiovascular mortality was respectively 23.7%, 12.2%, and 12.0%. Overall and cardiovascular annual cumulative mortality were significantly lower in the << special therapy >> than in the << free therapy >> group. The fixed combination of atenolol and chlorthalidone reduced mortality below that of the normotensives, independent of other cardiovascular risk factors.

Unexpected effects of coffee consumption on liver enzymes.

The effects of regular daily coffee consumption on liver enzymes were studied in a large number of subjects from the general population. In coffee drinkers, liver enzymes (gamma-glutamyl transferase, alanine-amino transferase, and alkaline phosphatase) and serum bilirubin were lower than in non-coffee-drinking subjects or in those consuming less than 3 cups daily. The hypothesis proposed is that liver enzymes are a target for caffeine contained in coffee.